298 KELLOGG AND BELL 



Considering the conditions of correlation, right and left and 

 segmental, it is obvious that the variations are influenced little 

 by bilateral symmetry or metemerism. 



Bateson, in his Materials for Variation (p. 415), records the 

 rinding by Brindley of 4-segmented feet (one or more) in 25 

 per cent, of a lot of adult individuals (number of individuals 

 not given) of Peri-planeta americana; in 15 per cent, of a lot 

 of Periplanela orientalis^ and of Blatta germanica, 16 out of 

 102 individuals had one or more 4-segmented tarsi. Brisout de 

 Barneville noted twenty years ago, or more, that a variation 

 from five to four tarsal segments occurred occasionally in each 

 of ten different species, representing four genera of cockroaches 

 (Blattidae). Bateson records one specimen, species not given 

 but evidently one of the three studied, as having all feet 4-seg- 

 mented, and says that there was a slightly greater frequency in 

 males than in females. 



It being suggested to Bateson that, in view of the known 

 power of regeneration of appendages, possessed by the Blattidas, 

 these variations might be due to incomplete regeneration after 

 mutilation, Bateson notes that in 200 just hatched individuals of 

 Periflaneta orientalis no 4-jointed tarsus was found, " while in 

 every instance of regeneration the new tarsus had four perfect 

 joints," and concludes that " there can be no doubt that in the 

 majority of cases, the 4-jointed tarsus had arisen on regeneration." 

 However, there is no difficulty in finding young roaches with 

 4-segmented feet. We have examined twenty immature indi- 

 viduals of Periplaneta americana belonging to the same collec- 

 tions lot as the adults referred to in the foregoing pages, and 

 note the following conditions : 



Class A; 14 individuals (n males, i female) had all the feet 



5-segmented. 

 " C; 2 individuals (males) had the right hind foot 



4-segmented. 

 " D; 2 individuals (males) had the left middle foot 



4-segmented. 

 " E; i individual (broken) had the right middle foot 



4-segmented. 

 " H ; i individual (male) had both hind feet 4-segmented. 



